The AC Propulsion Scion eBox is already equipped with the necessary circuitry and AC output to provide V2G services. A fleet of just 250 similar vehicles could earn $660,000 in annual ancillary services revenues, according to Dr. Tomic's research. Photo courtesy of Stefano Paris.

The V in V2G

A lot of people fret about what will happen to the electric power grid when there are millions of electric drive vehicles – battery, plug-in hybrids, both flexible fuel and fuel cell – trying to be recharged at the same time. Early studies indicate there is currently sufficient overnight capacity for a million or more EVs before additional capacity has to be built.

However, it now appears that, in fact, all those electric cars may actually reduce the need for additional capacity or at least slow its growth. That sounds counter-intuitive, especially if all those electric vehicles just take power from the grid. However, if instead they can return power to the grid some surprising things start to happen as will be pointed out in this three-part series on V2G or vehicle-to-grid systems.

Jasna Tomic, along with Willet Kempton and Steve Lentendre, is one of the leading researchers into the concept of V2G, which EV World has helped publicize starting back in 2001. In her presentation, she gives an overview of how even small fleets of a few hundred electric vehicles can realize not insignificant economic returns by being able to provide power regulating services to local utilities.

Tomic's definition of a V2G-suitable vehicle is one that produces and utilizes alternating current (AC), which is how power is delivered over the grid. She includes battery electric cars – both full-function, highway capable and “city” EVs with more limited speed and range capabilities – fuel cell vehicles with onboard reformers and ICE-hybrids, especially plug-in versions with larger capacity battery packs. She categorizes all of these under the “umbrella” of Electric Drive Vehicles or EDVs.

In the V2G vision, these EDVs not only are mobility machines but also power regulating devices both taking and giving power to the grid. From the consumer's perspective, this ability has immediate economic benefit because it offers a revenue stream that can help offset the higher cost of full-function electric vehicles like the Tesla Roadster or the AC Propulsion eBox.

Tomic noted that most vehicles are parked 96% percent of the time, which opens the door to the potential to turn the V2G-capable electric vehicle into a revenue source if it can be easily integrated into the power grid. In effect, the family car becomes a dual-use investment that provides transportation and community energy services, the latter helping offset the cost of the former.

She compared the current power generation “fleet” in the United States, which consists of some 9,000 units averaging 64,000 kW each, to the motor vehicle fleet. If only 25% of the current car and truck fleet were EDVs and each averaged 15kW of available onboard AC power, they would produce 750 gigawatts of energy, far in excess of the entire U.S. electric power industry, which today generates 602 gigawatts.

Even more persuasive are the economics. While electric power generators average 57% capacity, their per kilowatt capital cost is more than $1000. By contrast, Tomic calculates the capital cost in kilowatts for EDVs would be between $10-200, at a cost of between 10-50 cents per kilowatt hour.

Just as compelling was her “back of the envelope” calculation that indicated that if 50% of the U.S.'s 200 million vehicle fleet were EDVs that are driven an average of 15,000 miles a year, it would only represent 20% of the projected electrical power capacity of the country in 2020.

For Tomic, a far more interesting insight is that if those 100 million vehicles were V2G-ready and were available only 50% of the time – remember most cars are parked 96% of the time – those vehicles would provide sufficient distributed power to meet 70% of the nation's projected power capacity in 2002.

She envisioned four opportunities for V2G services, which she elaborates on in her presentation:

Ancilliary power services

Emergency power services

Renewable energy power storage

Electric transit power stablization

To hear her complete presentation, use either of the two MP3 players in the right-hand column or download the file to your computer for transfer and playback on your favorite MP3 device. Download her PowerPoint presentation here.

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